Impulse transmission



Dec. 1, 1942. DMQND 2,303,918

IMPULSE TRANSMISSION Filed March 7, 1941 3 Sheets-Sheet '1 FIG.

INVENTOR TILD/MOND BY I ,4 7' max/gr @e ca 1*,- Y4Z. 1 1 'DIMQND 2,303,918

IMPULSE TRANSMISSION Filed March 7, 1941' 3 Sheets-Sheet 2 //v VEN TOR 7; L DIMGND TWT ea. 1, i942. :r, L. DEMOND IMPULSE TRANSMISSION Filed March 7, 1941 rlinv: 3. 115. 11. nu m k Patented Dec. 1, 1942 IMPULSE TRANSMISSION Thomas L. Dimond, Rutherford, N. J assignor to Bell Telephone Laboratories, Incorporated, v New York, N. Y., a corporation or New York Application March '1, 1941, Serial No. 382,157

8 Claims.

This invention relates to the transmission of impulses and particularly to impulse repeaters used in telephone or other communication systems.

- 1 The objects of the invention are to simplify the structure and the operation of impulse repeaters; to obtain improvements in the registration and counting of the impulses; to enable the immediate seizure and operation ofan impulse repeater; and otherwise to improve these devices.

For some purposes it is desirable to use an impulse repeater in which each series of impulses is momentarily stored or registered and is then retransmitted. Usually the incoming series of impulses is registered on a stepping switch which advances and marks a terminal corresponding to the number of impulses; and the number of outgoing impulses is counted by a counting switch which steps over its terminals until'it reaches the position marked by the register switch.

According to the present invention'improvements are obtained over these prior repeating mechanisms by making use of magnetic elements for marking the number of impulses in an incoming series and'for counting the number of impulses in an outgoing series. More specifically afeature of thepresem invention is an impulse repeater comprising a series of magnetic elements preferably arranged along the arc of a circle, a magnetizing device which is driven by the incoming impulses over the series of elements to select and magnetize any desired element marking the number of incoming impulses, and a magnetically responsive device which is .driven in synchronism with theoutgoing impulses into operative relation with the successive magnetic elements until it reaches one that is magnetized. When a magnetized element is encountered, marking the number of impulsesi'n the incoming series, the magnetically operable device responds and terminates the transmission of the outgoing impulses.

One of the advantages of the present invention is that many 01' the moving magnetic parts, usually employed in impulse repeaters of this kind,

have been eliminated,'.and in place of these masnetically controlled elements have been substituted. f The foregoing and other features of the in vention will be described more fully in the following detailed specification.

In the drawings accompanying the specification:

repeating mechanism incorporating the features of this invention;

,Fig. 2 is a view of the opposite end-oi this device;

Fig. 3 is a front view of thestructure partly in cross-section;

Fig. 4 is an enlarged view of the magnetic relay which serves to count' the outgoing impulses; and

Fig. 5 shows the circuits of the repeater when applied to an automatic telephone system.

This invention may be used wherever it is desired to repeat series of impulses and particularly where it is'advantageous to store the iml5 pulses briefly and to retransmit them incorrected or modified form. vSuch a repeater is useful in automatic telephone systems where it is necessary to receive impulses from subscrib-v ers dials, from operators dials or from central oflice senders and to repeat them over outgoing circuits to switches or senders beyond. Although not so limited, the invention is applied, as illustrated in Fig. 5, to an outgoing repeater in a telephone system. It could, of course, be applied as equally as well to incoming. repeaters or to ,repeaters or re'generators when used for other purposes in systems of this kind.

The -structure oithe repeater, illustrated in Figs. 1, 2 and 3, includes a base or frame mem- ,30 her I having an annular-shaped plate 2 of nonmagnetic material secured thereto. The plate 2 supports a series of magnetic elements in the form of pins 8. These pins are fixed around the circumference of the annular plate 2, projecting aq iirom either side thereof as illustrated best in Fig.3. There may be any suitable number of pins in the series depending upon the require ments of the repeater, such as the number of c impulses necessary to send in each series and 40 the number of successive series that the re- '-;peater may-be called upon to receive and retransmit. These pins may be of any suitable magnetic material and are preferably made of some material that is readily magnetized and de- 45, magnetized.

The magnetizer, which serves to select and magnetize the pins 3, consists of an electromagnetic coil 6 wound about a core 5, which in turn is secured to the rotatable arm 6. The arm 6, which may be of any suitable insulating material, is attached to a shaft I, andthe latter is journalled for rotation in the upright supports a and s. The shaft '4 is driven in a step-bystepmovement to advance the magnetizer from Fig. 1 is a view showing one end ofan impulse each P position to the next y p e r ving magnet ll. The magnet it drives the shaft 1 by means of a stepping pawl H which engages the ratchet wheel l2 secured on the shaft. The shaft is held in any position to which it is advanced by means of a holding pawl l3 which also cooperates with the teeth of the ratchet wheel l2.

As soon as the magnetizing coil 4 has been advanced by the magnet I through the number of positions corresponding to the incoming series of impulses and is brought to rest with the core 5 in close proximity to the pin 3 in the selected position, the coil is energized to set up a magnetic field in the core 5 which magnetizes the selected pin. The circuit for energizing the coil 4 extends through the brushes l4 and 5 and the associated slip rings, mounted on the shaft 1 and insulated therefrom.

The number of outgoing impulses transmitted is counted by a counting mechanism including a magnetic relay I8. The relay l8, shown more clearly in Fig. 4, consists of a small vessel of glass or similar material within which the two flexible magnetic contacts I1 and I8 are sealed. These contacts are normally separated and are flexed into engagement with each other when the relay is adjacent to one of the magnetized pins 3. The magnetic relay I6 is mounted on the arm l8, which is rotatable to move the relay around the inner periphery of the annular plate 2, bringing said relay into close proximity with the successive pins 3. The arm is is rotated be assumed that the subscriber of line 34, shown in Fig. 5, is in the process of establishing a telephone connection by transmitting successive series of impulses. When the subscriber initiates a call, the line finder F operatesin the wellknown manner to seize the calling line, and, thereafter, selector switches including the switch S are operated in response to impulse series sent over the calling line to seize the outgoing repeater shown in detail in the drawings. The function of the repeater thus seized by the selector switch S is to repeat succeeding series of impulses over the trunk T outgoing to a distant omce where it appears in the bank of a finder switch F|. the purpose of which may be to extend the trunk to a series of selector switches or to a register sender.

As soon as the repeater is seized a circuit is closed from battery through the upper winding of the impulse relay 35, normal contacts of relay 38 thence over one side of the extended connection through the subscribers station including the dial 8! and returning over the other side the connection through the normal contacts of relay 88 and the lower Winding of relay to ground. Relay 35 operates and closes an obvious operating circuit for slow release relay 38. Relay 38 places a guarding ground potential on the sleeve conductor 39 and also closes an operating circuit for slow release relay 48. Relay 4!! closes the outgoing trunk to establish a circuit which may be traced from battery through the lower in a step-by-step movement bythe shaft 28,

which is Journalled in the upright supports 2| and 22. The stepping movement of the shaft 28 for advancing the magnetic relay l6 through the successive pin positions is effected by a stepping magnet 23 having a stepping pawl 24 which cooperates with the ratchet wheel 25 secured to the shaft. The holding pawl 2| serves to hold the shaft 20 centered with the relay IS in close proximity to the magnetic pin in the associated position. The circuit controlled by the magnetic contacts I! and I8 extends through the brushes 25 and 21 and the associated slip rings, which are mounted on the shaft 20 and insulated therefrom.

The rotating arm ID has an extension arm 28 thereon (Fig. 2) carrying a magnet 28 for the purpose of demagnetlzing the pins 3 over which it passes. The magnet 29 may be a permanent magnet, or, if desired, it may be energized by a 'coil over a circuit extending through brushes and slip rings on the shaft 28.

It will be noted that the shaft 1 carries a rotating arm 38 and that shaft 20 carries a similar a; I. They are made of conducting material and are in contact with each other when the magnetizer 5 and the magnetic relay l8 occupy the same position, that is, when the magnetizer and relay are in proximity to the same magnetic pin 3. These contact arms 33 and 8| are insulated from the shafts I and 25, respectively, to which they are attached. When they engage each other, a circuit is closed which leads through the brush 32 and its slip ring on the shaft I and through brush 33 and its slip ring on the shaft 28. This electrical circuit, as will be explained later, serves to determine when the impulse receiving or registering part of the repeater and the impulse counting or transmitting part of the repeater are occupying the same posi-' tion.

A description will now be given of the operation of the re: eater and for this purpose it may winding of line relay 44 at the distant oiiice, normal contacts of cut-off relay 45, conductor 48,

.uormal contacts of relay 41, closed contacts of relay 40, winding of polarized relay 48, retard coil 48, and in parallel through the normal contacts of relay 48, conductor 58, contacts of relay 45 to ground through the upper winding of relay 44. Line relay 44 operates and in the wellknown manner initiates the hunting operation of the finder switch F|. The current flowing over the trunk T in the circuit above traced is in the proper direction to operate the polarized relay 48 when the short circuit is removed by relay 43. Relay 4!] also closes an operating circuit for the off-normal relay 4|.

Assuming that the repeater is at rest at the moment it is seized by the switch S, the contact making arms 30 and 3| are in electrical engagement with each other, and the magnetizer 5 and relay l8 are occupying the same position. When, therefore, the off-normal relay 4| operates it closes a circuit from ground through the engaged contact arms 30 and 3|, winding of relay 42 to battery. Relay 4| also closes a circuit from ground through the inner left armature and contact of relay 5| to battery through the winding of relay 48. Relay 42 operates and closes a second circuit from ground through the contact of relay 4|, front contact of relay 42 and the winding of slow release relay 43 to battery and ground. Relay 43 operates and opens the short circuit around relay 48 and retard coil 49, permitting relay 48 to operate. Relay 43 also prepares a circuit for the supervisory relay 5|,

but this circuit is now opened at the back contacts of the operated relay 48. Furthermore relay 48 opens the impulse conductor 52 to preval.

relay $1, closed contacts of relay 50, conductor 54 to ground at the contact of relay If the pin. 3 opposite which the relay l5 was left on the last use of the repeater is sufiiciently magnetized at this time, the contacts l1 and i8 are still closed, and a parallel circuit for relay 53 may be traced through said contacts l1 and i8. Relay 53 operates and locks through its front contact and thence as above traced through the contacts of relay 5| and the contacts of relay it in parallel to ground on conductor 54.

. When, following the seizure of the repeater the calling subscriber transmits the next series of impulses, relay 35 releases and reoperates for each impulse of the series At each release of the relay 35 a circuit through the back contact of said relay, contacts of relay 38 and in parallel through the winding of slow release relay 5| and steppingmagnet l0. Relay 6| operates and remains energized throughout the series, and magnet It follows the impulses to step the shaft 1 and the magnetizer 5 through one position for each impulse in the series. At the end of the series relay 35 remains operated, and relay 6| releases after an inter- While relay 5| was operated it closed a charging circuit from battery through the resistance 52 for condenser 63. Upon the release of relay 6| the condenser 63 discharges and energizes the magnetizing coil d. Coil 5 magnetizes the core 5 and the pin 3 in the position to which the magnetizer has been driven by the incoming series of impulses. When the shaft 1 takes its first step in response to the first incoming impulse, the contact 30 disengages the contact 3|. The opening of these contacts causes the release of relay. Relay 42 opens one of the energizing circuits of relay 43, but relay 43 remains energized over the circuit traceable through the back contacts of relay 5| to grounded conductor 54 until the equipment at the distant ofllce is ready to receive the repeated impulses.

It will be recalled that the relay 54 at the distant oflice operates as soon as the trunk is seized and starts the movement of a switch, such as the line finder F-l, to attach a switch or a sender for receiving the repeated impulses. When the finder F--| has found the line, a ground po- 7 tential is applied over test brush 55 to operate the cut-off relay 45 and disconnect the line relay 46. At the same time, however, the trunk T is extended through the windings of the impulse receiving relay 55 associated with the switch or sender. This substitution of the relay 55 for the relay 45 causes a reversal in the direction of ourj rent flow over the trunkT, and relay 48 releases. Relay 48 closes anoperating circuit for the slow operate supervisory relay 5| which may be traced from battery through the winding of relay 5!, front contacts of relay 43, back contacts of relay 48 to ground on conductor 54. After an interval relay 5| operates and locks directly to conductor 54. The operation of relay 5| is a signal that the equipment at the distant office is ready to receive the repeated impulses. This signal is manifested by the opening of'the second holding circuit of relay 33, the first circuit having been opened by contacts 30 and BI in response to the first incoming series of impulses. Relay 53 now releases and closes the pulsing lead 52 so that outgoing impulses may proceed. Relay 43 also closes a short circuit around the relay 48 and coil 49 to improve the pulsing operation. Relay 5| opens one branch of the holding circuit of relay 53, and the latter relay releases unis closed from groundconductor 54.

the release of relay 33 a circuit is closed from ground through said interrupter, contacts of relay 4l, conductor 52, back contacts of relay 43, back contacts of relay 58, through the winding of relay 59 to battery. Relay 59 operates and prepares a circuit through its own winding and the winding of relay 58 in series through contacts of relays-d3 and 3! to ground. On the next opening of interrupter 5'! relay 58 energizes in series with relay 59 and extends the pulsing conductor 52 to the conductor 50. For each closure of the interrupter thereafter an impulse is sent over conductor 60 to the winding of the stepping magnet 23 and impulse relay 51. Each operation of the relay 5! opens the trunk circuit T to send an impulse to' the receiving relay 56 at the distant oilice. Each operation of the magnet 23 steps the shaft to and the magnetic relay Hi to the next succeeding position. On the first operation of relay 41, when the shaft 20 and relay i5 take the first step, the holding circuit of relay 53 is opened, and this relay releases, provided it had not previously released at the time relay 5| operated.

The shaft 20 continues to step in synchronism 'of the first series of'incoming impulses. Thereupon the contacts I! and i8 are closed, and after the completion of the open pulse by the release of relay 51, a circuit is completed from battery through the winding of relay 63. back contacts of relay 53, contacts "and I8, back contacts of relay 5?, contacts'of relay 40 to the grounded Relay 43 reoperates and opens the pulsing conductor 52 to terminate the transmission of the outgoing impulses and to stop the stepping movement of the shaft 20. Relay 33 also releases the relays 58 and 59. If in the meantime the calling subscriber has not transmitted the next series of impulses, the contact 3| engages contact 30, and relay 52 operates to close the alternate circuit for relay 43. Relay 43 reoperates relay 53 through the closed con tacts of relay l6, and relay 53 again locks through its own front contact as long as relay l8 remains operated and relay 41 released. If, however, the calling subscriber has commenced the transmission of thenext series prior to the time the relay it reaches the marked pin, no closure results between the contacts 3|! and 3|; or, as soon after the relay l6 reaches the pin marked by the preceding series of impulses as the subscriber commences the transmission of the succeeding series, contacts 3|) and 3| are disengaged to effect the release of relay 42. In either case the release of relay 42 on the one hand or its failure to operate on the other and the operation of relay 53 result in the release of relay 43 to reclose the pulsing conductor 52. Following the closure of conductor 52, relays59 and 58 operate to measure the interdigital space, following which relay 51 is repeatedly operated to transmit the next outgoing series and magnet 23 is operated in synchronism to advance the shaft 20,

until the. relay l5 reaches the magnetized pin marking the end of the next series of incoming impulses. When this next magnetized pin is This procedure continues until all impulse series have been received and retransmitted. Upon "the completion of the last series of impulses contacts 38 and 3i close, and relay- 42 operates, in turn operating relay 43. Relay 43 removes the short circuit from around relay 48 and coil 49 to include them in the supervisory circuit.

When the called subscriber answers, the direction of current flow over the trunk T is again reversed, and relay 48 operates. A circuit is now closed from battery through the winding of relay 36, front contacts of relays 5| and 48 to the f grounded conductor 54. Relay 38 operates and reverses the direction of current flow toward the calling subscriber's line thereby sending the usual supervisory signal.

Whenthe calling subscriber releases, which may occur either before or after the connection has been completed relay 3! releases, operating relay 8| and magnet l0. Relay 6| causes the recharging of condenser 63, and magnet ||I prepares to advancegtheshaft 1 to the next posi tion. After an interval relay 38 releases, and,

following 'a' further. interval, relay 6| releases, and the condenser 63 energizes the magnetizing coil 4 to magnetize the pin 3 in the position now occupied by the magnetizing coil 4. Relay; 38 removes ground potential from the hold conductor 38 to permit the release of the switches F and S and any other switches involved in the preceding train. Relay 38 releases relay 40 which extends the sleeve conductor 39 to ground on the front contact of relay 4|, thus guarding the repeater against seizure. Relay 48 also opens the outgoing trunk T to permit the release oi the equipment in the distant ofllce. Relay 4| remains looked through the back contacts of relay 42, assuming that contacts 38 and 3| are separated at this time. The release of relay 40 opens the holding circuit of relay 53 and also prevents the reclosure of the circuit-for. relay 43. pulsing conductor 52 for stepping the magnet 23 to advance the shaft 28 until contacts 38 and 3| are closed. When this occurs relay 42 operates and releases relay 4|. Relay 4| in turn releases relay 42. Thus the receiving and trans- Hence relay 43 releases and recloses the,

mitting parts of the repeater are restored to the same position, and the repeater circuits are fully restored to normal.

What is claimed is: 1. In combination, a repeater comprising a series of magnetic elements, means movable in response to a series of incoming impulses for selecting a corresponding one of said elements, means for magnetizing the selected elements, an impv' transmitter 'forgenerating and transmit'ting outgoing impulses, a counting mechanism including a magnetic device, means responsive to said impulse transmitter for moving said device into operative relation to the sucin sai magnetizer serving tomagnetize ,the selected magnetic element to mark the number'- of m pulses received, a transmitter for generating and transmitting outgoing impulses, a inagnetic device movable into proximity with each of the successive magneticelements of said series. means cooperating with said impulse transmitter for moving said magnetic device in synchronism with the outgoing impulses until it reaches the magnetized element, the magnetism of said element serving to operate the magnetic device,

and means controlled by the operation of said magnetic device for disabling the impulse generator to determine pulses.

3. In combination, an impulse repeater comprising a plurality of stationary magnetic elements arranged in a series of positions, a magthe outgoing series of imnetizer movable from one position to the next and into proximity with each of the magnetic elements of the series, means responsive to the magnetism of the magnetized element when it moves into the position occupiedby said magnetized element, and means responsive to the operation of said magnetic device for terminating the outgoing series of impulses.

4. The combination in an impulse repeater of a plurality of magnetic elements arranged in a series of positions, a magnetizer movable from position to position and into proximity with each of said magnetic elements, means responsive to the impulses of an incoming series for advancing said-magnetizer from any one of said positions to a succeeding position representing the number of impulses received, means for energizing said magne rto magnetize the magnetic element succeeding position, a counting mechanism including a magnetic device movable from position to position and into proximity with each of .said magnetic elements, a transmitter for cessive magnetic elements of said series, said device being operated magnetically when it moves into operative relation to said magnetized element, and means responsive to the operation of said magnetic device for terminating the transmission of the outgoing impulses.

2. In combination, a repeater comprising a series of stationary magnetic elements, a magnetizer movable into proximity with each of the successive magnetic elements in saidseries,

.means responsive to a series of incoming impulses for moving said magnetizer into proximity with the particular magnetic element representing the number oi impulses received, said generating and transmitting outgoing impulses,

means responsive to the incoming impulses for rendering said impulse transmitter eflective to transmit the outgoing impulses, means controlled by :said impulse transmitter for advancing said counting mechanism through successive positions to bring said magnetic device into proximity with the magnetized element, the magnetism of said element serving to operate said magnetic device, and means controlled by said magnetic device for terminating the transmission of the outgoing impulses.

5. The combination in an impulse repeater of a plurality oi stationary magnetic elements arranged in a series of positions, a magnetizer movable from one position to another and into operative ments, means responsive to incoming impulses for advancing said magnetizer .in a stepping movement from any position to a succeeding position representing the number of incoming impulses, means for energizingsaid magnetizer to magnetize the element in said succeeding position, a transmitter for generating and transmitrelation to each of said magnetic elenetizer to magnetize the impulse series,

ting outgoing impulses, means responsive to the incoming impulses for rendering said transmitter efiective to transmit outgoing impulses, means including a magnetic relay movable through said series of positions and into operable relation with each one of said magnetic elements, means controlled by said impulse transmitter for driving said relay in a stepping movement through a number of positions corresponding to the number of outgoing impulses transmitted, said magnetic relay being operated when it moves into aposition occupied by a magnetized magnetic element, andmeans controlled by the operation of said relay for terminating the transmission of the outgoing impulses.

6. The combination in an impulse repeater of a plurality of magnetic elements arranged in a series of positions. amagnetizer movable through positions of said series and into operative relation to each of said magnetic elements, means responsive to successive series of impulses for moving said magnetizer from any position to suc-.

seeding positions, each of which corresponds to the number of impulses in each of the successive incoming series, means for 'ements in the positions corresponding respectively to each of said 4 means for detecting the magnetized elements, means for transmitting series of outgoing impulses, and means controlled by said detecting means for determining the number of impulses in each of said outgoing series.

I. In combination, an impulse repeater, means for seizing saidrepeater to repeat a series incoming impulses, saidrepeater including a causing said magtion' with each of series'of magnetic elements,

impulse transmitter iorgenerating and trans nism including a magnetic device, means the magnetized element in .and means controlled outgoing impulses.

the number of impulses in said incoming series,

means for causing said magnetizer to magnetizethe selected magnetic element, transmitting means for generating and transmitting a series of outgoing impulses corresponding to said incoming impulses, a magnetic relay movable from one position to the next and into operative relapulse transmitting means for advancing said magnetic relay into the position selected by said magnetizer in response'to the incoming impulses, said magnetic relay being-operated by 'erated for terminating. the transmission of the a repeater comprising a means movable in response to a series of incoming impulses for selecting a corresponding one of said elements, means for magnetizing the selected element, an

.8. In combination,

mitting outgoing impulses, a counting mecharesponsive to said impulse transmitter formoving said device into operative, relation to the successive magnetic elementsof said series, said device being operated magnetically when it moves into operative relation to said magnetized element,

means responsive to the operation of said masplurality of magnetic elements arranged in 9.

netic device for terminating the transmission oi the outgoing impulses, and means for danagnetizing said magnetized element,

nnmoa I said magnetic elements, means I responsive to the incoming impulses after the the selected position. by said relay when op- 

